1. Field of the Invention
The present invention relates to an antenna, and in particular relates to an aperture antenna transmitting a circularly polarized signal.
2. Description of the Related Art
FIGS. 1a and 1b show a conventional antenna 1 for transmitting a circularly polarized signal. The antenna 1 comprises a substrate 10, a radiator 20 and a ground layer 30. The substrate 10 comprises a first surface and a second surface. The first surface is opposite to the second surface. The radiator 20 is disposed on the first surface. The ground layer 30 is disposed on the second surface. The radiator 20 is rectangular, and comprises a beveled corner 21. FIG. 1b is a sectional view along direction I-I of FIG. 1, wherein a signal line 41 is electrically connected to the radiator 20 passing through the substrate 10.
A conventional antenna provides an axial ratio bandwidth of about 3˜5%, which does not satisfy wideband circularly polarized signal transmission.